A guide to the Thalassinidea (Crustacea: Malacostraca: Decapoda) of the South Atlantic Bight

Ghost shrimp and mud shrimp in the decapod infraorder Thalassinidea are ecologically important members of many benthic intertidal and shallow subtidal infaunal communities, largely due to the sediment filtration and mixing that result from their burrowing and feeding behavior. These activities considerably modify their immediate environment and have made these cryptic animals extremely interesting to scientists in terms of their behavior, ecology, and classification. Over 20 years ago, seven species of thalassinideans were known from the South Atlantic Bight (Cape Hatteras, NC to Cape Canaveral, FL). During this study, the examination of extensive collections from the National Museum of Natural History (NMNH), the Southeastern Regional Taxonomic Center (SERTC), and regional institutions, resulted in the identification of 14 species of thalassinideans currently known to occur within this region. The family Axiidae is represented by three species: Axius armatus, Calaxius jenneri, and Paraxiopsis gracilimana; the Callianassidae by six: Biffarius biformis, B. cf. fragilis, Callichirus major, Cheramus marginatus, Gilvossius setimanus, and Necallianassa berylae; the Calocarididae by two: Calocaris templemani and Acanthaxius hirsutimanus; and the families Laomediidae, Thomassiniidae, and Upogebiidae are each represented by one: Naushonia crangonoides, Crosniera wennerae, and Upogebia affinis, respectively. An illustrated key is presented for species level identification and supplemental notes on the ecology, distribution, and taxonomy of the species are provided.(PDF file contains 38 pages.)

SPEECH RECOGNITION IN VODIS II.

VODIS II, a research system in which recognition is based on the conventional one-pass connected-word algorithm extended in two ways, is described. Syntactic constraints can now be applied directly via context-free-grammar rules, and the algorithm generates a lattice of candidate word matches rather than a single globally optimal sequence. This lattice is then processed by a chart parser and an intelligent dialogue controller to obtain the most plausible interpretations of the input. A key feature of the VODIS II architecture is that the concept of an abstract word model allows the system to be used with different pattern-matching technologies and hardware. The current system implements the word models on a real-time dynamic-time-warping recognizer.

The use of syntax and multiple alternatives in the VODIS voice operated database inquiry system

The paper describes the architecture of VODIS, a voice operated database inquiry system, and presents some experiments which investigate the effects on performance of varying the level of a priori syntactic constraints. The VODIS system includes a novel mechanism for incorporating context-free grammatical constraints directly into the word recognition algorithm. This allows the degree of a priori constraint to be smoothly varied and provides for the controlled generation of multiple alternatives. The results show that when the spoken input deviates from the predefined task grammar, a combination of weak a priori syntax rules in conjunction with full a posteriori parsing on a lattice of alternative word matches provides the most robust recognition performance. © 1991.

The origin of new genes: Glimpses from the young and old

Genome data have revealed great variation in the numbers of genes in different organisms, which indicates that there is a fundamental process of genome evolution: the origin of new genes. However, there has been little opportunity to explore how genes with new functions originate and evolve. The study of ancient genes has highlighted the antiquity and general importance of some mechanisms of gene origination, and recent observations of young genes at early stages in their evolution have unveiled unexpected molecular and evolutionary processes.

Nucleotide variation and recombination along the fourth chromosome in Drosophila simulans

The fourth chromosome of Drosophila melanogaster and its sister species are believed to be nonrecombining and have been a model system for testing predictions of the effects of selection on linked, neutral variation. We recently examined nucleotide variat

M_2RSbO_6:R~(3+)复合氧化物的合成组成结构和性能的研究(M = Ba、Sr、Ca, R = La、Gd、Y、Bi, R' = Sm、Eu、Dy、Ho、Er、Tm)

对于稀土与非稀土所组成的二元复合氧化物的研究国外已有较多的报导。但是，对于稀土和锑的复合氧化物只是近年来才开始有些研究工作。含锑与稀土的多元复合氧化物的报导就更少。本文在我们实验室张静筠等人三元复合氧化物研究的基础上，开展Mo—Sb_2O_5—R_2O_3—R'_2O_3—Bi_2O_3多元体系的研究工作，这对于我国丰产元素稀土和锑的应用以及利用Bi~(3+)的激活与敏化将是有益的。本文按Thornton等人的方法合成了Ba_2BiSbO_6，Ba_2GdSbO_6，按EγΦECEHKO等人的方法合成了M_2RSbO_6 (M = Ba、Sr、Ca, R = La Y)。并以M_2RSbO_6为基质，掺Sm~(3+)、Eu~(3+)、Dy~(3+)、Ho~(3+)、Er~(3+)、Tm~(3+)和Bi~(3+)，研究它们的化学组成，晶体结构与发光性能的关系及规律，Bi~(3+)的荧光和敏作用。同时研究了它们的磁学和热学性能。化学组成的分析结果表明，计算的含量与实验测得的含量符合较好，说明化学反应是按化学计量比进行的。通过X-射线粉沫物相分析和晶胞参数的理论计算确定M_2RSbO_6(M = Ba、Sr、R = La、Y、Gd、Bi)复合氧化物是属于立方钙钛太型化合物。空间群为Fm3m，点群为Oh。用计算机计算了Ca_2YSbO_6的晶胞参数并结合荧光光谱分析确定它属于畸变的单斜钙钛矿，空间群为P_(21)。用磁天平测量了样品M_2RSbO_6 (M = Ba、Sr、Ca; R = Gd、Y、Bi)的磁化率。除Ba_2GdSbO_6是顺磁性物质外共余的都是反磁性的物质。按所用原料Sb_2O_5计算的磁化率与测量值符合较好，表明在所研究的M_2RSbO_6化合物中锑是正五价的。用热重热差分析仪测量了样品在反应中的热性能，观察到在化合物形成的过程中所用原料Sb_2O_3大约在520 ℃左右氧化变为Sb_2O_5。除所用原料碳酸盐分解外没有挥发性的物质，这就进一步证明化学组成分析和磁化率测量的结果是正确的。光学测量的结果表明，所有的磷光体随着激活离子浓度的不同其光谱都发生规律性的变化。对于不同Eu~(3+)浓度的Ba_2YSbO_6:Eu~(3+)和Br_2YSbO_6:Eu~(3+), Bi~(3+)体系用254nm激发时均能观察到Eu~(3+)于595nm的尖峰发射。用基质和Bi~(3+)的激发峰325nm激发时，明显地看到敏化剂Bi~(3+)到Eu~(3+)的能量传递，使Eu~(3+)于595nm的发射大大增强，我们认为Bi~(3+)对Eu~(3+)的敏化作用是由于基质和Bi~(3+)的~1S。→ 3P_1的跃迁吸收了激发的能量，然后无辐射弛豫到Eu~(3+)的激发态~5D_0，产生~5D_0 → 7F_1的磁偶极跃迁。对于不同Eu~(3+)浓度的Sr_2YSbO_6:Eu~(3+)和Sr_2YSbO_6:Eu~(3+), Bi~(3+)体系用245nm激发时均能观察到Eu~(3+)于595nm的尖峰发射。用基质和Bi~(3+)的激发峰335nm激发时，观察到基质和Bi~(3+)对Eu~(3+)具有某种能量传递。敏化作用机理与上述的Ba_2YSbO_6:Eu~(3+)和Ba_2YSbO_6:Eu~(3+), Bi~(3+)体系相同。对于不同Eu~(3+)浓度的Ca_2YSbO_6:Eu~(3+)和Ca_2YSbO_6:Eu~(3+), Bi~(3+)体系用396nm激发时，均能观察到Eu~(3+)于613nm很强的尖峰发射。用基质和Bi~(3+)的激发峰313nm激发时，见到Bi~(3+)和基质对Eu~(3+)具有某种能量传递，这种敏化作用主要是由于基质和Bi~(3+)的3P_1 → ~1S_0的400nm的宽带发射和Eu~(3+)的~7F_0 → ~5L_6的396nm的吸收相匹配产生~5L_6→~5D_0→~7F_2的跃迁。通过对激发光谱和荧光光谱的分析给出了Ca_2Y_(0.96)Eu_(0.04)SbO_6的能级图，从实验上可见，Eu~(3+)的发光强烈地依赖于钙钛矿的结构，当Eu~(3+)在空间群为Fm3m 的Ba_2YSbO_6和Sr_2YSbO_6中处于Oh点对称性时，主要是~5D_0 → ~7F_1的磁偶极跃迁。当Eu~(3+)在空间群为P_(21)的单斜钙钛矿中时，主要是~5D_0 → ~7F_2的电偶极跃迁。对于不同掺杂浓度M_2YSbO_6:R~(13+)(M = Ba、Ca; R' = Sm、Dy、Ho、Er、Tm)体系，通过激发和荧光光谱的研究，合理地确定了谱项。发现基质对Sm~(3+)、Dy~(3+)、Ho~(3+)具有敏化作用。对不同Bi~(3+)浓度的Ca_2YSbO_6:Bi~(3+)，由激发和荧光光谱可见Bi~(3+)具有二个激发带，第一激发带位于240nm处相当于~1S_0 → ~1P_1的跃迁，第二激发带位于315nm处相当于~1S_0 → ~3P_1的跃迁。有一个很强的兰紫色发射位于400nm处相当于~3P_1 →~1S_0的跃迁。

Imaging of musculoskeletal bacterial infections by [124I]FIAU-PET/CT.

BACKGROUND: Traditional imaging techniques for the localization and monitoring of bacterial infections, although reasonably sensitive, suffer from a lack of specificity. This is particularly true for musculoskeletal infections. Bacteria possess a thymidine kinase (TK) whose substrate specificity is distinct from that of the major human TK. The substrate specificity difference has been exploited to develop a new imaging technique that can detect the presence of viable bacteria. METHODOLOGY/PRINCIPAL FINDINGS: Eight subjects with suspected musculoskeletal infections and one healthy control were studied by a combination of [(124)I]FIAU-positron emission tomography and CT ([(124)I]FIAU-PET/CT). All patients with proven musculoskeletal infections demonstrated positive [(124)I]FIAU-PET/CT signals in the sites of concern at two hours after radiopharmaceutical administration. No adverse reactions with FIAU were observed. CONCLUSIONS/SIGNIFICANCE: [(124)I]FIAU-PET/CT is a promising new method for imaging bacterial infections.

Federal Nutrition Assistance at Farmers’ Markets: Evaluating Self-Efficacy and the Home Nutrition Environment

SNAP and WIC help alleviate food insecurity among low-income families; however, some still struggle with fruit and vegetable accessibility. Farmers' markets present the opportunity to purchase fresher foods than other food retailers; therefore, we chose this environment to conduct our research. A survey of 70 WIC/SNAP shoppers at three D.C. metropolitan area farmers' markets assessed the correlation between parental self-efficacy and the home nutrition environment (composed of family health behavior, perceived barriers, and fruit and vegetable offerings in the home) and found a significant relationship. Interviews were used to evaluate market accessibility, SNAP/WIC benefit redemption, and the feasibility of accepting these benefits. Both market participants and coordinators mentioned the greater variety and superior quality of farmers' market produce but also suggested several improvements. Findings suggest that SNAP incentive programs may increase fruit and vegetable purchases. Programs targeting consumer self efficacy may also produce positive outcomes.